Such a type of lock device, provided with an opening-and-closing body which opens and closes an opening in a vehicle body, a lock mechanism which switches between an open state, a half-latched state and a fully-latched state in accordance with the amount of opening of the opening-and-closing body, and an electronic control unit (ECU) which is operated in a microcomputer normal power mode or a microcomputer power-saving power mode, is known in the art. Various switches for detecting the state of the lock device are connected to the electronic control unit. The electronic control unit is provided with a microcomputer that includes a switch monitor which monitors the ON/OFF state of each switch.
The electronic control unit, in the microcomputer normal power mode, monitors each switch at a predetermined clock frequency via the switch monitor of the microcomputer. Whereas, in the microcomputer power-saving mode, the electronic control unit stops the monitoring of each switch at a predetermined clock frequency via the switch monitor of the microcomputer, or monitors at a clock frequency that is lower than the predetermined clock frequency.
In an electronic control unit of the related art, when the electronic control unit is operated in the microcomputer normal power mode, the microcomputer normal power mode is only transferred to the microcomputer power-saving mode when a predetermined amount of time has lapsed when the lock device remains at a fully-latched state.